STAINING, PRACTICAL AND THEORETICAL 



CONGO RED 



Michrome No. 400. Molecular weight 697. An acid dis-azo dye, 

 pH g-2S*- Solubility at 15° C: water 5%, absolute alcohol 075%. 



NH2 



N=N 



N=N 



SOsNa 



DIANIL BLUE 2R 



Michrome No. 302. Molecular weight 845. An acid dis-azo dye, 

 pHy2S*. Solubility at 15° C: water 5%, absolute alcohol o-oi%. 



CHc 



OH OH 



N=N- 

 NaOaS- 



SOsNa 



OH 



N=N 



CH3 



SOsNa 



* 1% in neutral distilled water; see pages 17 and 29. 



48 



